1. Technical Field
The present invention relates to a light source device and an image projecting apparatus having the same.
2. Description of the Related Art
The light source device may be used for a projector (image projecting apparatus) that projects a screen of a personal computer, a video image, or an image based on image data stored in a memory card, on a screen. Generally, the projector focuses light emitted from the light source device, on an image forming unit such as a micromirror display device referred to as a digital micromirror device (DMD) or a liquid crystal panel. In alternative to a high-luminance discharge lamp, the recent light source device may be implemented by a solid-state light emitting element that emits excitation light, and a phosphor (wavelength conversion member) that absorbs the excitation light and converts the excitation light into light having a predetermined wavelength range.
In the case where the light source device is applied to an image projecting apparatus requiring particularly high brightness, the disadvantage of an increase in temperature of the light emitting element becomes serious, such that the light emitting element needs to be cooled. Since the light is irradiated on the phosphor after the excitation light emitted by the light emitting element is focused to increase light density, large heat releasing occurs at a position corresponding to a focusing spot of the phosphor even in the case of a slight loss of light of the fluorescent material. In addition, in the case where the fluorescent material converts a wavelength of the excitation light, heat releasing occurs due to a loss. As a result, the heat releasing due to the loss of light and the heat releasing due to the loss during the wavelength conversion are combined, so that the temperature of the phosphor becomes very high. If the temperature of the phosphor becomes high, the material such as an organic binder included in the phosphor is degenerated, or an fluorescent light emission amount of the fluorescent material is decreased (temperature quenching), and as a result, there occurs a problem in that wavelength conversion efficiency of the phosphor is decreased. Thus, the phosphor also needs to be cooled.